Support is requested for a Research Scientist Development Award for five years of work on the implications for mental health services research of recent contributions to developmental epidemiology. Developmental epidemiology is concerned with understanding the causes, course, and outcomes of disorders within the context of human development. Services research, as well as being an important area of substantive research in its own right. is a critically important tool for testing scientific hypotheses about the development of alcohol, drug, and mental (ADM) disorders. The treated and untreated course of most disorders, and thus the services needed, may differ widely as a function of the developmental status of the individual. The impact of both normal and abnormal development on the causes, course, treatment and outcomes of ADM disorders has recently begun to receive serious attention, but the implications for mental health services research have so far remained unexplored. One reason is that there are few researchers with sufficient exposure to the tenets and methods current in developmental psychopathology, epidemiology, and mental health services research, to be able to establish the crosswalks needed for others to follow. As one of those few researchers, the aim of this submission is to use the time liberated by an RSDA to deepen the applicant's knowledge in relevant areas, and to develop a new paradigm for child and adolescent mental health services research. Specific aims are: (1) building on previous theoretical work from the applicant's Developmental Epidemiology Program, to examine ways in which the mental health service system for children and youth can provide "natural experiments" that illuminate the causes, course, and outcomes of ADM disorders; (2) to test hypotheses generated by the theoretical work using data collected for one or more ongoing studies, particularly the Great Smoky Mountains Study, a longitudinal study of service use for ADM disorders in rural youth; (3) to work with colleagues in mental health services research (Burns, Morrissey), developmental science (Cairns, Cicchetti), and epidemiology and statistics (Stangl, Pickels to obtain a deeper understanding of the issues involved in each area, as it applies to the theme of this submission; (4) to produce scientific papers and books that will help to integrate services research and developmental epidemiology as aspects of the same research process, so that future studies, whether clinical or epidemiological, will incrementally increase our understanding of, and ability to prevent, ADM disorders.